To live or let die? Epigenetic adaptations to climate change-a review

Abstract

Anthropogenic activities are responsible for a wide array of environmental disturbances that threaten biodiversity. Climate change, encompassing temperature increases, ocean acidification, increased salinity, droughts, and floods caused by frequent extreme weather events, represents one of the most significant environmental alterations. These drastic challenges pose ecological constraints, with over a million species expected to disappear in the coming years. Therefore, organisms must adapt or face potential extinctions. Adaptations can occur not only through genetic changes but also through non-genetic mechanisms, which often confer faster acclimatization and wider variability ranges than their genetic counterparts. Among these non-genetic mechanisms are epigenetics defined as the study of molecules and mechanisms that can perpetuate alternative gene activity states in the context of the same DNA sequence. Epigenetics has received increased attention in the past decades, as epigenetic mechanisms are sensitive to a wide array of environmental cues, and epimutations spread faster through populations than genetic mutations. Epimutations can be neutral, deleterious, or adaptative and can be transmitted to subsequent generations, making them crucial factors in both long- and short-term responses to environmental fluctuations, such as climate change. In this review, we compile existing evidence of epigenetic involvement in acclimatization and adaptation to climate change and discuss derived perspectives and remaining challenges in the field of environmental epigenetics. Graphical Abstract.

Figure 1.

Schematic overview of epigenetic adaptations in response to heat stress and potential outcomes. The compilation of studies across various organisms has revealed the involvement of epigenetic processes following heat exposure. These processes include DNA hypomethylation at gene promoters, DNA N6-methyldeoxyadenine, histone acetylation and methylation, and histone variants (epigenetic processes box upperline). They contribute to chromatin remodeling and the activation of specific genes involved in immune response, heat-stress response, and detoxification. Correlative phenotypic effects such as enhanced thermotolerance and increased fitness (survival, lifespan, and reproductive success) have been observed (phenotypical outcomes box). In addition, specific epigenetic patterns have been described in gametes and during embryonic development (epigenetic processes box bottomline), suggesting the potential for epigenetic memory and inheritance for up to five offspring generation. The schema has been created using BioRender.com.